Process for producing alcohol

ABSTRACT

The invention provides a process for producing an alcohol, including the step of hydrogenating a glyceride in the presence of a catalyst, adding water, or a process for producing an alcohol, including the step of hydrogenating a glyceride in the presence of a catalyst and in the presence of from 0.5 or more of water per mole of the starting glyceride.

FIELD OF THE INVENTION

The present invention relates to a process for producing an alcohol bycatalytic hydrogenation reaction of a glyceride.

In the industrial production of a fatty alcohol, a process for producinga fatty alcohol by transesterificating glyceride with methanol, and thencatalytically hydrogenating the resulting fatty ester of methanol isconventionally preferably used. Alternatively, a process ofcatalytically hydrogenating a wax ester obtained by esterifying ahydrolyzed fatty acid with a fatty alcohol is conventionally preferablyused. A valuable glycerin product can be obtained this way at a highyield and at a high purity. The economical advantage of this 2-stageprocess is recognized.

On the other hand, the direct catalytic hydrogenation of glycerideenables an industrially important product such as a fatty alcohol to bedirectly obtained from naturally available fats and oils, but such aprocess is not generally used in industrial production. This is becausea side reaction in which initially formed glycerin is hydrogenated onthe surface of a catalyst occurs in the direct catalytic hydrogenationof glyceride, and thus glycerin cannot be obtained at a high yield.

From an economical viewpoint, the direct catalytic hydrogenation processcannot accordingly compete with the 2-stage process described above.This is also a reason that the process of directly hydrogenatingtriglycerides is not used on an industrial scale.

The method of obtaining a fatty alcohol by directly hydrogenatingglyceride is described for example in U.S. Pat. No. 2,094,127, U.S. Pat.No. 2,109,844 or U.S. Pat. No. 2,241,417.

DE-A 1668219 describes a method of hydrogenating glyceride obtained fromfats and oils.

Methods of directly hydrogenating glyceride are also described in U.S.Pat. No. 4,942,266, U.S. Pat. No. 4,954,664, U.S. Pat. No. 4,982,020,U.S. Pat. No. 5,364,986 or U.S. Pat. No. 5,475,160.

SUMMARY OF THE INVENTION

The present invention provides a process for producing an alcohol,including the step of hydrogenating a glyceride in the presence of acatalyst and added water.

In addition, the invention provides a process for producing an alcohol,comprising the step of hydrogenating a glyceride in the presence of acatalyst and 0.5 mole or more of water per mole of glyceride.

DETAILED DESCRIPTION OF THE INVENTION

The method described in U.S. Pat. No. 2,094,127, U.S. Pat. No. 2,109,844or U.S. Pat. No. 2,241,417 is carried out at a reaction temperature of200 to 400° C. at a hydrogen pressure of 100 to 300 bar to produce afatty alcohol, but the desired reaction product glycerin is obtainedonly in a small amount and instead a large amount of propane, propanolor propylene glycol is obtained.

DE-A 1668219 describes a problem that a side reaction to producepropylene glycol, propanol or propane in place of the desired glycerincannot be controlled.

In the methods described in U.S. Pat. No. 4,942,266, U.S. Pat. No.4,954,664, U.S. Pat. No. 4,982,020, U.S. Pat. No. 5,364,986 and U.S.Pat. No. 5,475,160, the direct hydrogenation of glyceride to a fattyalcohol is conducted with a copper-based catalyst under relatively mildreaction conditions. 1,2-propanediol is produced at a high yield, andthe process is not directed to the production of glycerin.

The present invention provides an economically extremely excellentprocess for producing an alcohol by the hydrogenation reaction ofglyceride as a starting material in the presence of a catalyst, wherein,for example, glycerin having a high purity can be recovered.

The process for producing an alcohol according to the present inventionis economically excellent and industrially extremely advantageousbecause, for example, decomposition of glycerin can be suppressed andglycerin having a high purity can be recovered.

In a preferred process of the present invention, the catalytichydrogenation reaction of glyceride is carried out by adding water or inthe co-presence of water. The amount of water is preferably 0.5 mole ormore per mole of glyceride from the viewpoint of improvement of glycerinselectivity, more preferably 1 mole or more, even more preferably 2moles or more, even more preferably 3 moles or more. With respect toenergy consumption, the amount of water is preferably 10,000 moles orless per mole of glyceride, more preferably 5,000 moles or less, evenmore preferably 1,000 moles or less, even more preferably 500 moles orless.

The method of adding water or allowing water to be co-existent in thereaction is not particularly limited, and water may be added or beco-existent in either a gas or a liquid state. For example, there is amethod wherein glyceride and water are previously mixed and fed to areactor, a method wherein glyceride and water or water vapor are mixedbefore being fed to a reactor and then fed to the reactor, or a methodwherein water or water vapor is added during the reaction.

Water formed by the reaction may be allowed to be co-existent during thehydrogenation reaction. The reaction to form water is hydrogenation,esterification, dehydration or condensation etc. For example a mixtureof glyceride and a fatty acid may be fed to a reactor and water producedby hydrogenation of the fatty acid may be made to co-exist in thereactor. The amount of fatty acid is preferably from 0.5 to 10,000 molesper mole of glyceride from the viewpoint of the amount of water producedby the reaction, more preferably from 1 to 5,000 moles, even morepreferably from 3 to 500 moles.

The fatty acid used is not limited in the invention, but includespreferably fatty acids derived from vegetable oils such as soy bean oil,rape seed oil, coconut oil, palm oil or palm kernel oil or animal oilsuch as beef tallow or fish oil. A mixture of fatty acids may be used.

Both water and a fatty acid may be added or made to co-exist in thehydrogenation reaction of glyceride.

In the present invention, the pressure in the catalytic hydrogenationreaction is preferably 1 to 50 MPa, more preferably 2 to 30 MPa. Thetemperature is preferably 120 to 300° C., more preferably 150 to 280° C.

The reactor used in the production process of the present invention isnot particularly limited insofar as the catalytic hydrogenation reactionis feasible, and the reactor may be an ordinarily used device. Examplesof the reactor include a fluidized bed reactor wherein catalytichydrogenation reaction is carried out with a catalyst dispersed influid, a moving bed reactor wherein the catalytic hydrogenation reactionis carried out with fluid supplied while the entire catalyst layer dropsgradually due to gravitational force, a fixed bed reactor wherein thecatalytic hydrogenation reaction is carried out by supplying a fluidhaving a catalyst charged and immobilized therein, a multi-tube fixedbed reactor wherein the temperature of a catalyst layer can beisothermal, and a batch reactor wherein hydrogenation is carried out ina container charged with a catalyst, a starting material and water.

The glyceride used as a starting material in the present invention isnot particularly limited, and known materials such as triglyceride,diglyceride and monoglyceride can be used. The triglyceride includes,for example, vegetable oils such as soybean oil, rapeseed oil, coconutoil, palm oil and palm kernel oil, animal oils such as tallow and fishoil, and synthetic triglyceride. The starting glycerides may be usedsingly or as a mixture of two or more thereof. As the glycerides, eitherthose subjected to pretreatment such as a de-acid treatment ordesulfurization treatment or those not subjected to any pretreatment maybe used.

The catalyst used in the present invention may be a hydrogenationcatalyst used in known alcohol production, and is not particularlylimited. For example, a Cu-based catalyst such as Cu/Cr, Cu/Zn etc.,Co-based catalyst such as Co/Mo, Co/Zr etc., and catalysts based onnoble metals such as Re, Ru, Rh and platinum can be used. Among thesecatalysts, the Ru-based catalyst and Co-based catalyst are preferable,and further the Co-based catalyst, particularly the Co/Zr catalyst ismore preferable.

The form of the catalyst is not particularly limited, and can besuitably selected from the forms of powder, granules, tablets, noodles,film, etc. When a catalyst precursor is used, the catalyst is obtainedby reduction with a reducing substance. The reducing substance used hereincludes hydrogen, carbon monoxide, ammonia, hydrazine, formaldehyde andmethanol, and these reducing substances may be used singly or as amixture thereof and may be used in the presence of an inert gas such asnitrogen. When the catalyst precursor is reduced, either a gas phasereduction method or a liquid phase reduction method conducted in ahydrocarbon such as liquid paraffin or in a solvent such as dioxane,alcohol or ester may be used.

The alcohol obtained by the production process of the present inventionis glycerin and a fatty alcohol derived from a fatty acid constitutingthe starting glyceride, and together with the fatty alcohol, glycerincan be recovered at a high yield.

The following examples further describe and demonstrate embodiments ofthe present invention. The examples are given solely for the purpose ofillustration and are not to be construed as limitations of the presentinvention.

EXAMPLES

In Examples 1 to 4 and Comparative Examples 1 to 3, shown below, palmkernel oil (saponification value 244.8 mg KOH/g; water content 0.05% byweight; acid value 0.17 mg-KOH/g) subjected to de-acid treatment wasused as the starting triglyceride.

Example 1

A commercial Co/Zr catalyst (G-67 manufactured by Süd-Chemie Inc.) wasmilled in a mortar and activated under the conditions of hydrogenpressure of 5 MPa, a temperature of 250° C, and 0.5 hour.

A 500-ml autoclave in a rotating stirring system was charged with 7.5 gof the commercial Co/Zr powdery catalyst subjected to the activationtreatment, 150 g of starting triglyceride and 3 moles of water per moleof the starting glyceride. The mixture was heated to 230° C. andsubjected to catalytic hydrogenation reaction for 3 hours under theconditions of a total pressure of 24.5 MPa and a stirring rate of 900r/min.

Samples obtained during the reaction and after conclusion of thereaction were separated with water into an oil phase and aqueous phase,and the degree of conversion of triglyceride, the content of fattyalcohol in the oil phase and the glycerin selectivity were analyzedrespectively by gas chromatography. The degree of conversion oftriglyceride is defined by the following equation:Degree of conversion of triglyceride (%)=(1−TGt/100)×100wherein TGt is the amount (wt %) of triglyceride in the oil phase

The glycerin selectivity is defined as the ratio (wt %) of glycerin tothe total organic material in the aqueous phase detected by gaschromatography. The material other than the fatty alcohol in the oilphase was mainly wax ester, monoglyceride and diglyceride, and thematerial other than glycerin in the aqueous phase was mainly propyleneglycol, n-propanol and iso-propanol. The results after 3 hours of thereaction are shown in Table 1.

Example 2

After heating to 230° C., catalytic hydrogenation reaction was carriedout for 5 hours under the conditions of a total pressure of 24.5 MPa anda stirring rate of 900 r/min in the same manner as in Example 1 exceptthat the amount of added water was 20 moles per mole of the startingglyceride. The degree of conversion of triglyceride, the content offatty alcohol in the oil phase and the glycerin selectivity after 3 and5 hours of the reaction, respectively, were analyzed in the same manneras in Example 1. Results are shown in Table 1.

Example 3

After heating to 230° C., catalytic hydrogenation reaction was carriedout for 7 hours under the conditions of a total pressure of 24.5 MPa anda stirring rate of 900-r/min in the same manner as in Example 1 exceptthat the amount of added water was 50 moles per mole of the startingglyceride. The degree of conversion of triglyceride, the content offatty alcohol in the oil phase and the glycerin selectivity after 6 and7 hours of the reaction were analyzed in the same manner as inExample 1. Results are shown in Table 1.

Comparative Example 1

After heating to 230° C., catalytic hydrogenation reaction was carriedout for 5 hours under the conditions of a total pressure of 24.5 MPa anda stirring rate of 900 r/min in the same manner as in Example 1 exceptthat water was not added. The degree of conversion of triglyceride, thecontent of fatty alcohol in the oil phase and the glycerin selectivityafter 5 hours of the reaction were analyzed in the same manner as inExample 1. Results are shown in Table 1.

Comparative Example 2

A commercial powdery Cu/Cr catalyst (KSC-1 manufactured by NikkiChemical Co., Ltd.) was activated under the same conditions as inExample 1. A 500-ml autoclave in a rotating stirring system was chargedwith 3 g of the thus activated commercial Cu/Cr powdery catalyst and 200g starting triglyceride, and the mixture was heated to 230° C. andsubjected to catalytic hydrogenation reaction for 5 hours under theconditions of a total pressure of 24.5 MPa and a stirring rate of 900r/min. The degree of conversion of triglyceride after 5 hours, thecontent of fatty alcohol in the oil phase and the glycerin selectivityafter 5 hours of the reaction were analyzed in the same manner as inExample 1. Results are shown in Table 1.

TABLE 1 Degree of Content of convertion of fatty alcohol GlycerineReactiontime triglyceride in oil phase selectivity (hour) (%) (weight %)(%) Example 1 3 99.3 31.1 61.5 Example 2 3 98.0 46.1 81.6 5 99.8 69.836.2 Example 3 6 100 57.9 79.5 7 100 63.8 57.3 Comparative 5 27.2 4.6<0.1 example 1 Comparative 5 99.8 62.7 0.4 example 2

Comparative Example 3

In a reactor having an inner diameter of 25 mm, equipped with a fixedbed filled with 300 cc of a commercially available Co/Zr catalyst (G-67manufactured by Süd-Chemie Inc.), a catalytic hydrogenation was carriedout at a pressure of 19.8 MPa, at a temperature of the catalyst bed of230° C., at a hydrogen mole ratio of 75 to the starting oil and fat. Thetemperature of a heater provided in front of the reactor was 290° C. sothat the temperature of the starting triglyceride and water in thecatalyst bed was 230° C. The starting triglyceride was supplied to thereactor at a flow rate of 120 cc/h. At the outlet of the reactor, theconversion of triglyceride, the content of fatty alcohol in the oilphase and selectivity of glycerin were determined in the same way asExample 1. Results are shown in Table 2.

Example 4

According to the method of Comparative Example 3, the startingtriglyceride at a flow rate of 60 cc/h and water in 50 moles per mole ofglyceride were fed to a reactor, and the degree of conversion oftriglyceride, the content of fatty alcohol in the oil phase and theglycerin selectivity at the outlet of the reactor were analyzed in thesame manner as in Example 1. Results are shown in Table 2.

TABLE 2 Degree of convertion of Content of fatty Glycerine triglyceridealcohol in oil phase selectivity (%) (weight-%) (%) Comparative 74.140.0 1.0 example 3 Example 4 97.0 44.8 48.3

Example 5

A 500-ml autoclave in a rotating stirring system was charged with astarting material (saponification value 247.3 mg-KOH/g; acid value 210.4mg-KOH/g) including 0.75 g of triglyceride, 4.88 g of diglyceride and6.38 g of monoglyceride in a palm kernel oil composition and 111.12 g ofmixed fatty acids in a palm kernel oil composition, and water in 115moles per mole of glyceride. The amount of water produced from thestarting fatty acid by hydrogenation was calculated to be 16 moles permole of the starting glyceride. For the reaction, 13 g of a commercialCo/Zr catalyst (G-67 manufactured by Süd-ChemieInc.) was used, and themixture was heated to 230° C. and then subjected to catalytichydrogenation reaction under the conditions of a total pressure of 24.5MPa and a stirring rate of 900 r/min for 7 hours. The catalyst had beenpreliminarily activated under the conditions of a hydrogen pressure of 5MPa, a temperature of 250° C. and 4 hours. The degree of conversion ofglyceride is defined by the following equation:The degree of conversion of glyceride(%)=(1−[glyceride]_(t)/[glyceride]₀)×100wherein [glyceride]_(t) is the sum (wt%) of triglyceride, diglycerideand monoglyceride in the oil phase after 7 hours of the reaction, and[glyceride]₀ is the sum (wt %) of triglyceride, diglyceride andmonoglyceride in the starting material.

The glycerin selectivity was analyzed in the same manner as in Examples1 to 4 and Comparative Examples 1 to 3. Results are shown in Table 3.

TABLE 3 Degree of convertion of Content of fatty Glycerine triglyceridealcohol in oil phase selectivity (%) (weight-%) (%) Example 5 86.4 40.663.3

As can be seen from the results in Table 1, 2 and 3, glycerin wasobtained at a high yield together with fatty alcohol in Examples 1 to 5.In Comparative Example 1, on the other hand, the degree of conversion oftriglyceride was low, and the yield of fatty alcohol was low. Theorganic material in the aqueous phase was decomposed glycerin products,that is, propylene glycol, n-propanol and iso-propanol, and glycerin wasnot detected. In Comparative Example 2 and 3, the majority of theorganic material in the aqueous phase was decomposed glycerin products,that is, propylene glycol, n-propanol and iso-propanol, and the glycerinselectivity was very low.

1. A process for producing glycerin and an alcohol, comprisinghydrogenating a glyceride in the presence of a catalyst and added water,thereby producing said glycerin and alcohol, wherein the alcohol isderived from the acid constituting the glyceride.
 2. A process forproducing glycerin and an alcohol, comprising hydrogenating a glyceridein the presence of a catalyst and 0.5 mole or more of water per mole ofglyceride, thereby producing said glycerin and alcohol, wherein thealcohol is derived from the acid constituting the glyceride.
 3. Theprocess according to claim 2, wherein all or a part of the water isproduced by a reaction other than said hydrogenating of said glyceridein the presence of said catalyst and said water.
 4. The processaccording to claim 1 or 2, wherein the hydrogenating is conducted in thepresence of a fatty acid.
 5. The process according to claim 1 or 2,wherein the hydrogenating is conducted by adding a fatty acid.
 6. Theprocess according to claim 1 or 2, wherein the alcohol is a fattyalcohol.
 7. The process according to claim 2, wherein the amount ofwater per mole of glyceride is 1 mole or more.
 8. The process accordingto claim 2, wherein the amount of water per mole of glyceride is 2 molesor more.
 9. The process according to claim 2, wherein the amount ofwater per mole of glyceride is 3 moles or more.
 10. The process.according to claim 1 or 2, wherein the glyceride comprises atriglyceride.
 11. The process. according to claim 10, wherein thetriglyceride is derived from palm kernel oil.
 12. The process accordingto claim 1, wherein the amount of water per mole of glyceride is 1 moleor more.
 13. The process according to claim 1, wherein the amount ofwater per mole of glyceride is 2 moles or more.
 14. The processaccording to claim 1, wherein the amount of water per mole of glycerideis 3 moles or more.
 15. The process according to claim 1 or 2, whereinthe hydrogenating is carried out at a pressure of 1 to 50 MPa.
 16. Theprocess according to claim 1 or 2, wherein the hydrogenating is carriedout at a pressure of 2 to 30 MPa.
 17. The process according to claim 1or 2, wherein the hydrogenating is carried out at a temperature of 120to 300° C.
 18. The process according to claim 1 or 2, wherein thehydrogenating is carried out at a temperature of 150 to 280° C.